The present disclosure relates to a touch panel.
A touch sensing apparatus such as a touch screen, a touch pad, or the like, which is an input apparatus attached to a display apparatus to provide an intuitive input method to a user, has recently been widely used in various electronic devices such as a cellular phone, a personal digital assistant (PDA), a navigation device, and the like. Particularly, as demand for a smart phone has increased, a touch screen capable of providing various input methods within a limited form factor has been increasingly used.
The touch screen used in a portable device may mainly be divided into a resistive type touch screen and a capacitive type touch screen according to a method of sensing a touch input. Here, the capacitive type touch screen has advantages in that it has a relatively long lifespan and that it may easily implement various input methods and gestures, such that the use thereof has been increasing. Particularly, since the capacitive type touch screen may implement a multi-touch interface more easily as compared with the resistive type touch screen, it is widely used for devices such as a smart phone and the like.
The capacitive type touch screen includes a plurality of electrodes having a predetermined pattern and defining a plurality of nodes at which a capacitance change is generated by a touch input. At the plurality of nodes distributed on a two-dimensional plane, a self-capacitance or mutual-capacitance change is generated by the touch input. A coordinate of the touch input may be calculated by applying a weighted average method, or the like, to the capacitance change generated at the plurality of nodes.
In a touch panel according to the related art, a sensing electrode that recognizes touch is generally formed of indium tin oxide (ITO). However, the ITO is expensive and has low price competitiveness, because indium, used as a raw material thereof, is a rare earth metal. In addition, indium is expected to be depleted within the next decade, such that it may not be sufficiently supplied.
Thus, research into technology of forming the electrode using non-transparent conductive fine lines for reasons mentioned above has been conducted. Here, the electrode formed by the conductive fine lines such as a metal may have better conductivity than that of the ITO or conductive polymer and may be sufficiently supplied.
In order to implement the touch panel as described above, a multi-layer structure should be implemented.
Particularly, the touch panel using the conductive fine lines has a structure in which a metal electrode is mainly formed on an insulating material.
In order to implement the touch panel when the metal electrode is formed on the insulating material, adhesion between the metal electrode and the insulating material should be secured.